Microchannel compression reactor assembly

ABSTRACT

The present invention includes a removable microchannel unit including an inlet orifice and an outlet orifice in fluid communication with a plurality of microchannels distributed throughout the removable microchannel unit, and a pressurized vessel adapted have the removable microchannel unit mounted thereto, the pressurized vessel adapted to contain a pressurized fluid exerting a positive gauge pressure upon at least a portion of the exterior of the removable microchannel unit. The invention also includes a microchannel unit assembly comprising a microchannel unit operation carried out within a pressurized vessel, where pressurized vessel includes a pressurized fluid exerting a positive gauge pressure upon an exterior of the microchannel unit operation, and where the microchannel unit operation includes an outlet orifice in fluid communication with an interior of the pressurized vessel.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 11/052,455,filed Feb. 7, 2005, now U.S. Pat. No. ______, which is acontinuation-in-part of application Ser. No. 10/774,298, filed Feb. 6,2004, the disclosures of which are incorporated herein by reference.

BACKGROUND

1. Field of the Invention

The present invention is directed to chemical processing unit operationsand, more specifically, to microchannel-based chemical processing unitoperations.

2. Background of the Invention

The present disclosure is related to unit operations where at least aportion of the unit operation is in compression; and more particularly,to unit operations where at least a portion of the unit operation iscontained within a pressure vessel and maintained in compression.

Prior art disclosures, such as U.S. Pat. No. 5,167,930, disclose asealed chamber encasing a reactor, where the pressure within the sealedchamber equals that of the reactor. The equalization of pressuresbetween reactor and chamber is maintained by providing an expandablereactor and an expandable sealed chamber that accommodated for suchchanges.

Other prior art disclosures, such as U.S. Pat. No. 3,515,520, disclose areactor with an internal corrosion resistant sleeve adapted to receive acatalyst and/or a corrosive reactant therein. The sleeve is jacketed bya higher-pressure flow of a non-corrosive reactant to prohibit leaks inthe sleeve from leaking the corrosive reactant and/or catalyst andmaking contact with the exterior reactor walls. The non-corrosivereactant enters the sleeve through an opening and exits via anotheropening in fluid communication with the catalyst/corrosive reactant andis thereafter consumed through the normal reaction process.

Still further prior art disclosures, such as U.S. Pat. No. 2,462,517,disclose a multiple walled reactor where an internal, first wallconfines the reaction chamber, and a second wall defines a cavityoccupied by a pressurized atmosphere, and a third wall defines a cavityoccupied by a cooling fluid. The pressurized atmosphere is used toregulate the external reactor vessel pressure, while the cooling fluidis used to regulate the thermal energy within the pressurized reservoirand the reactor.

SUMMARY OF THE INVENTION

The present invention is directed to microchannel-based chemicalprocessing unit operations. A first exemplary embodiment includesmultiple microchannel processing unit operations (“microchannel processunits”) at least partially contained within a pressurized vessel. Thepressurized nature of the vessel acts as a pressure balance upon themicrochannel process units as the pressure exerted upon the exterior ofthe process units approximates the pressures exerted upon the interiorof the process units by the processes carried out within themicrochannels.

More specifically, the present invention includes microchannel processunits that are removable from a pressurized vessel. An exemplaryembodiment disclosed herein provides a pressurized vessel havingconduits adapted to carry materials to and from the microchannel processunits. In this manner, a docking structure associated with the vesselenables the process units to be removed, replaced, and/or reinstalledwithout requiring total or partial destruction of the pressurizedvessel, the conduits, or the microchannel process units. In instanceswhere one or more of the microchannel process units includes amicrochannel reactor having catalyst retained within the microchannels,refurbishment of the catalyst can occur at a remote location from thevessel without utilizing the conduits of the vessel or requiringadditional conduits to be constructed to provide access to the reactorsthrough the vessel. In sum, the ability to remove and/or reinstall themicrochannel process units from the pressure vessel simplifies theprocess for modifying, testing, and replacing the units prior tooperation of the units within a pressurized environment, such as thatprovided by the vessel.

The present invention also includes an exemplary embodiment for carryingout a Fischer-Tropsch synthesis within a fixed or removable microchannelprocess unit housed at least partially within a pressurized vessel.Fischer-Tropsch synthesis reacts carbon monoxide and hydrogen in thepresence of a catalyst to create higher molecular weight hydrocarbons.These higher molecular weight hydrocarbons provide the potential forpartial solidification that might clog the microchannels of amicrochannel process unit if the solids content of the streams is toogreat. To reduce the likelihood of a clog, the exemplary embodimentinjects an elevated temperature fluid into the downstream sections ofthe microchannel process units to elevate the temperature of the productstream carrying the Fischer-Tropsch synthesis products to maintain afluid flow within the microchannels. Before the elevated temperaturefluid enters the microchannel process unit, a counter current heatexchanger is established between the conduit carrying the elevatedtemperature fluid and the conduit carrying the product of theFischer-Tropsch synthesis so that farther downstream sections of theproduct conduit are contacted by higher elevated temperature fluid toensure fluid flow. The exemplary embodiment also capitalizes upon theexothermic Fischer-Tropsch synthesis to provide steam for this or otherprocesses within a chemical facility.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevated perspective view of a first exemplary embodimentof the present invention;

FIG. 2 is an elevated perspective view of the first exemplary embodimentwith an exploded view of a microchannel process unit, flange, andgaskets.

FIG. 3 is a cross-sectional view of the first exemplary embodiment;

FIG. 4 is an elevated perspective view of a first exemplary structurefor use in fabricating the first exemplary embodiment;

FIG. 5 is an elevated perspective view of a second exemplary structurefor use in fabricating the first exemplary embodiment;

FIG. 6 is an elevated perspective view of a third exemplary structurefor use in fabricating the first exemplary embodiment;

FIG. 7 is an elevated perspective view of a fourth exemplary structurefor use in fabricating the first exemplary embodiment;

FIG. 8 is an elevated perspective view of a fifth exemplary structurefor use in fabricating the first exemplary embodiment;

FIG. 9 is an elevated perspective view of a sixth exemplary structurefor use in fabricating the first exemplary embodiment;

FIG. 10 is an elevated perspective view of a seventh exemplary structurefor use in fabricating the first exemplary embodiment;

FIG. 11 is an elevated perspective view of an eighth exemplary structurefor use in fabricating the first exemplary embodiment;

FIG. 12 is an elevated perspective view of the first exemplaryembodiment without the microchannel process units installed;

FIG. 13 is an elevated cross sectional view of a first alternateexemplary embodiment;

FIG. 14 is an elevated perspective view of a second exemplaryembodiment;

FIG. 15 is a right-side view of the second exemplary embodiment of FIG.14;

FIG. 16 is a frontal view of the second exemplary embodiment of FIG. 14;

FIG. 17 is a right-side, cross-sectional view of the second exemplaryembodiment of FIG. 14;

FIG. 18 is a frontal, cross-sectional view of the second exemplaryembodiment of FIG. 14;

FIG. 19 is an elevated perspective view from the front of the secondexemplary embodiment of FIG. 14, with the shell of the pressure vesselremoved; and

FIG. 20 is an elevated perspective view from the rear of the secondexemplary embodiment of FIG. 14, with the shell of the pressure vesselremoved.

DETAILED DESCRIPTION

The exemplary embodiments of the present invention are described andillustrated below to include microchannel-based chemical process unitoperations. The various orientational, positional, and reference termsused to describe the elements of the invention with respect to oneanother have been chosen with respect to a single point of reference forclarity and precision. Therefore, it will be understood that thepositional and orientational terms used to describe the elements of theexemplary embodiments of the present invention are only used to describethe elements in relation to one another. Thus, variations envisioned byone of ordinary skill shall concurrently fall within the scope of thedisclosure of this invention.

Referring to FIGS. 1-3, a first exemplary embodiment of the presentinvention includes a microchannel unit operation assembly 10. Themicrochannel unit operation assembly 10 includes a cylindricalpressurized vessel 12 that defines an interior cavity bounded by acylindrical wall 14 and two end caps 16, 18. An entrance orifice and anexit orifice (not shown) through the rear end cap 16 provide access tothe interior cavity and are operative to supply or remove a pressurizedfluid housed within the vessel 12. A dock 20 is mounted to the top ofthe vessel 12 and runs the majority of the longitudinal length of thevessel 12. The dock 20 circumscribes a rectangular opening 22 within thecylindrical wall 14 and defines five generally rectangular openings 24that are operative to receive five removable microchannel process units26. As will be discussed in more detail below, the microchannel processunits 26 include at least one side that is tapered and adapted to restupon a correspondingly tapered surface of the dock 20. Thereafter, arectangular flange 28 bolts to the dock 20 (and optionally to the unit26) and is operative to sandwich a gasket assembly 30, 30′ between eachprocess unit 26 and the dock 20. The first gasket assembly 30 isoperative to seal the rectangular opening in the dock 20 occupied by themicrochannel process units 26 and seal an interface between the flange28 and each process unit 26, while the second gasket assembly 30′ isoperative to seal the interface between the openings within the processunit 26 and the openings on the side of the dock 20.

A series of conduits 32, 34, 36, 38 are mounted to the vessel 12 and areadapted to direct fluid streams into, or away from, each of themicrochannel process units 26. Each microchannel process unit 26includes a series of microchannels adapted to be in fluid communicationwith the conduits mounted to the vessel 12. Three of the conduits 32,34, 36 are operative to carry input streams, while one conduit 38carries an output stream. A second output stream is exhausted at the topof each microchannel process unit 26 through the rectangular opening 40in the flange 28 and gasket assembly 30.

For purposes of explanation only, the microchannel process unit 26includes a microchannel reactor 26 operative to carry out two concurrentreactions. While various reactions may be carried out within amicrochannel reactor 26, for purposes of explanation, it is presumedthat the microchannel reactor 26 will carry out a combustion reactionand a syngas reaction (where methane and stream are reacted to generateprimarily carbon monoxide and hydrogen gas). In such an exemplarycombustion reaction, a fluid fuel stream, which may consist of carbondioxide, hydrogen, methane, and carbon monoxide, is carried through thefirst input conduit 32 and directed to a first set of microchannelswithin the reactor 26. The second input conduit 34 is operative to carryan oxygen-rich fluid, which may consist of air, that is directed to asecond set of microchannels within the reactor 26. The second set ofmicrochannels is operative to direct the oxygen-rich fluid into directcontact with the fuel stream flowing within a downstream section of thefirst set of microchannels. This downstream section includes distributedcatalyst that facilitates a combustion reaction between the oxygen-richfluid and the fuel stream generating thermal energy and reactionproducts. The catalyst may line the walls of the downstream section ofthe first set of microchannels or be retained within the microchannelsin another manner.

The downstream section of the first set of microchannels is in intimatecontact with a third set of microchannels containing a reactant streamdelivered thereto by the third input conduit 36. The reactant streamincludes a pressurized mixture of steam and methane that utilize thethermal energy generated by the combustion reaction, in the presence ofa catalyst, to drive an endothermic syngas (steam reformation) reactionwhere the product stream is rich in hydrogen gas. The exhaust of thecombustion reaction is vented through openings 40 within the top of thereactor 26, while the steam reformation products are directed out of thereactor 26 and into the first output stream 38 for further processingdownstream. Exemplary pressures exerted upon the microchannels of thereactor for these reactions include pressures at or above 335 psig. Inorder to reduce the stress upon the microchannels, the reactors 26 areat least partially surrounded by a pressurized fluid within the vessel12 operative to provide a pressure balance by exerting a pressure ofapproximately 335 psig. In order to exert such pressures upon theexterior of the reactors 26, the pressurized vessel 12 must befabricated to withstand these pressures for extended periods. Thefollowing is an exemplary sequence to fabricate the pressurized vessel12 and associated conduits 32, 34, 36, 38 in accordance with the presentinvention, based upon a cylindrical vessel 12 having a diameter ofthirty-six inches.

Referring to FIG. 4, a preliminary frame 100 includes a rectangularmetal bar 102 having five sets of four dove-tailed rectangular openings104 formed therethrough that are each separated by a series of metalblocks 106. Exemplary dimensions for the bar 102 include 160 inches inlength, 12.15 inches in width, and 2.38 inches in thickness, whileexemplary dimensions for each block 106 include 4.00 inches in length,12.15 inches in width, and 7.24 inches in thickness. The metal blocks106 are mounted to an interior surface 108 of the bar 102 at apredetermined angle that, as will be discussed below, can vary between±45 degrees from perpendicular. Each of the four rectangular openings104 has a dimension of 27.19 inches length, 12.15 inches width with thedepth corresponding to the thickness of the bar. Ten sets of gasketingmaterial 110 are mounted to a channel (not shown) within the interiorsurface 108 of the bar 102, with each set of gasketing material 110surrounding two (top two 112 or bottom two 114) of the four dove-tailedopenings 104. Exemplary gasketing material 110 for use with the presentinvention includes, without limitation, Garlock Helicoflex SpringEnergized Seals, metal/graphite gaskets, reinforced graphite, corrugatedmetal/spiral wound gaskets, and elastomeric seals. As discussedpreviously, the gasketing material 110 is operative to provide a fluidicseal between the interior surface 108 of the bar 102 and an exteriorsurface of the microchannel process unit (see FIG. 2, 30′). Two mirrorimage frames 100 are constructed so that the metal blocks 106 of eachframe face one another and the exterior surfaces 116 of each bar 102face away from one another.

Referencing FIGS. 5 and 6, an arcuate metal strip 118 is welded to theexterior surface 116 of each bar 102. As will be apparent below, themetal strip 118 is incorporated into the overall structure to define thecylindrical vessel 12 (see FIG. 1) and, therefore, has an arcrepresentative of a 9.69 inch wide longitudinal section of a thirty-sixinch cylinder. The metal strip 118 runs the entire length of the bar 102and is operative to divide the top two 112 and bottom two 114rectangular openings 104. A 10 inch pipe segment 120 is welded to theunderneath side 122 of the strip 118 and welded to the exterior surface116 of the bar 102 to create a longitudinal conduit 124 supplying thebottom 114 openings. Two arcuate extensions 126, 128 are aligned withthe ends of the metal strip 118 and welded to respective ends of theframe 100, which includes mounting the extensions 126, 128 to the endsof the strip 118, bar 102, and block 106. The arcuate extensions 126,128 are representative of a 19.65 inch segment of a thirty-six inchdiameter cylinder, with the first extension 126 having a width W1 of20.00 inches, and the second extension 128 having a width W2 of 6.00inches.

Referencing FIG. 7, a ten inch pipe segment 140 is welded to theexterior 116 of the bar 102, the strip 118, the block 106, and theextensions 126, 128 to provide a separate longitudinal conduit 142feeding the top 112 series of openings. This conduit 142 runs inparallel with the conduit 124 feeding the bottom two 114 series ofopenings. A notch is cut from the segment 140 prior to welding in orderto allow the front aspect 143 to match the contours of the ends of thebar 102, the block 106, and top surface of the first extension 126.

Referencing FIGS. 8 and 9, end caps 144, 146 contacting the ends of thetwo respective segments 120, 140, the bar 102, and the far block 106 arewelded above and below the second extension 128 in order to enclose theends of the conduits 124, 142.

Referring to FIG. 10, an opposing end 148 of the first conduit 124receives an adapter 150 operative to redirect the flow of materials in adirection other than along the linear longitudinal length of the bar102. The adapter 150 comprises a ten inch pipe segment 152 and an endcap 154 contoured to match the arc of the underside of the firstextension 126. A six inch pipe segment 156 is circumferentially weldedto an orifice (not shown) in the ten inch pipe segment 152 to provide adown tube. The resulting structure comprises an intermediate frame 160.

Referencing FIG. 11, the two, mirror image intermediate frames 160 arejoined by welding a series of block spacers 162 between opposing blocks106, resulting in five rectangular openings 164 within the top of theeventual vessel 12 (see FIG. 12). A corresponding spacer 166, 168 iswelded between the extensions 126,128 and to the block spacers 162 andopposing blocks 106 in order to bridge the gap between the extensions.An elbow pipe 170 is welded to the circumferential opening of eachadapter 150, where the elbow pipe has an extension pipe 172 weldedthereto.

Referring to FIG. 12, a semicircular pipe 172 is welded to the opposingends 174 of each strip 118 and extensions 126, 128 to provide acontinuous cylindrical body 176 (outside of the openings 154). A rearend cap 180 and a front end cap 182 are welded to the cylindrical body176 to enclose the 36 inch diameter opening on each end. The rear endcap 180 includes two flanged pipes (not shown) providing fluidcommunication with the interior of the vessel 12. The front end cap 182includes two orifices 184 adapted to allow the pair of extension pipes172 to pass therethrough as the cap is oriented to abut the opening atthe front of the cylindrical body 176. A first circumferential weldmounts the body 176 to the rear cap 180, and a second circumferentialweld mounts the front cap 182 to the body 176. A third set ofcircumferential welds is operative to close the front end of the vessel12 by sealing any gap between the openings 184 and the extension pipes172 piercing the openings 184. A flange 186 is mounted to each end ofthe respective extension pipes 172 and is adapted to mate with apreexisting flanged conduit (not shown). Two ten inch flanged pipes 188are respectively contoured to match the exterior shape of the vessel 12and welded to the ends of the pipe sections 140 and to the exterior ofthe vessel 12. The flanges at the end of the pipe 188 are adapted tomate with a preexisting flanged conduit (not shown) upon installation ofthe vessel 12.

The resulting vessel 12 is operative to provide sealed fluidcommunication between the flanged openings 190, 192, 194, 196 and theopenings 112, 114 along the interior sides of the vessel 12. Morespecifically, the first flanged opening 190 provides the sealed conduit32 (see FIG. 1) in fluid communication with the top openings 112longitudinally spaced along the left hand side 200 of the vessel,whereas the second flanged opening 192 provides the sealed conduit 34(see FIG. 1) in fluid communication with the top openings 112longitudinally spaced along the right hand side 202 of the vessel. Thethird flanged opening 194 provides the sealed conduit 38 (see FIG. 1) influid communication with the bottom openings 114 longitudinally spacedalong the right hand side 202 of the vessel, whereas the fourth flangedopening 196 provides the sealed conduit 36 (see FIG. 1) in fluidcommunication with the bottom openings 114 longitudinally spaced alongthe left hand side 200 of the vessel.

As discussed above, the orientation of the blocks 106 with respect tothe bar 102 may be manipulated during fabrication to angle the openings112, 114 with respect to completely vertical, such as tapering theopenings 112, 114 inward (from bottom to top) or tapering the openings112, 114 outward (from bottom to top). Other methods operative to anglethe openings with respect to completely vertical will become obvious tothose of ordinary skill, and all such methods and apparatusesconcurrently fall within the scope of the present invention. Bymanipulating the dimensions of the opening 164, is it possible tosuspend the microchannel process unit 26 within the opening. Forexample, if each bar 102 is oriented outward 5 degrees (from bottom totop) from vertical, a V-shaped profile is provided along at least oneplane of the opening 164 (see FIG. 3). If the microchannel process unit26 is correspondingly shaped to taper inward from top to bottom to matchthe taper of the opening 164, it is possible to vertically suspend thereactor from the dock 20 without requiring the process unit 26 to berigidly mounted to the dock, such as by welding.

Referring to FIG. 13, an alternate configuration 100′ may be utilized ininstances where the operating pressure exerted upon the process unit 26′by the fluid within the vessel 12′ will be a positive gauge pressure,tending to push the process unit 26′ out of the opening 164′, it may beadvantageous to orient each bar 102′ inward 5 degrees (from bottom totop) from vertical to provide an inverted V-shaped profile orfrustropyramidal portion is provided along at least one plane of theopening 164′ so that higher pressures tend to push a process unit 26′with a correspondingly inverted V-shaped profile more tightly againstthe dock 20′. In such an instance, the process unit 26′ may include aflange 28′ or other attachment point to mount the unit 26′ to thedock/vessel 20′/12′. It is to be understood either approach (taperedinward or tapered outward) could be utilized in conditions calling forpositive or negative operational gauge pressures to be exerted upon theprocess unit 26, 26′ by the contained fluid of the vessel 12, 12′.

Several advantages are apparent from the exemplary embodiments of thepresent invention. For example, by making the microchannel process unit26 removable from the vessel 12, replacement of the units 26 is mademuch easier, as opposed to prior methods requiring cutting the weldsbetween the units and the vessel 12. Welding of the units 26 alsointroduced high local temperatures that tended to degrade or destroycatalyst in proximity to the weld and/or result in delaminations. Inaddition, by making the units 26 removable by simply twisting a fewbolts, refurbishment of catalyst within the reactor units may beaccomplished without the need for separate catalyst refurbishment linespiercing the pressure vessel 12 and units.

Other advantages of making the microchannel process units 26 removableinclude the removal or replacement of individual units 26 (as opposed toa bank of units), the ability to refurbish active metal catalysts awayfrom the pressure vessel 12, and the ability to pressure test or performother tests upon the process unit 26 away from the pressure vessel 12.

Referencing FIGS. 14-16, a second exemplary embodiment of the presentinvention includes a Fischer-Tropsch reactor assembly 300. The reactorassembly includes a pressurized vessel 302 consisting of a hollowcylindrical shell 304 sealed at its ends by a front end cap 306 and arear end cap 308. The front end cap 306 includes three orifices thatreceive three corresponding flanged conduits 310, 312, 314 that extendinto the interior of the shell 304. Two other flanged conduits 316, 318are received by two orifices within the shell 304 and providecommunication with the interior of the shell. Each end cap 306, 308 ismounted circumferentially to the cylindrical shell to provide a fluidtight seal therebetween. Exemplary techniques for mounting the end caps306, 308 to the cylindrical shell 304 include, without limitation,welding and flanged connections utilizing torqued bolts. Each flangedconduits 310, 312, 314, 316, 318 is circumferentially welded to acorresponding opening within the vessel 302 in order to mount theconduits to the vessel and ensure the vessel is capable of beingpressurized and maintaining such pressure.

For purposes of explanation only, the Fischer-Tropsch reactor assembly300 is adapted to carry out a Fisher-Tropsch synthesis where carbonmonoxide and hydrogen within a feed stream are converted into highermolecular weight hydrocarbons in the presence of a catalyst. Morespecifically, the higher molecular weight hydrocarbons include C₅₋₁₀₀paraffins, oxygenates, and olefins. In order to increase the yield ofdesired products, the dissipation of thermal energy away from thereactive zones of a Fischer-Tropsch reactor is important, as thereaction is highly exothermic.

Referencing FIG. 17, the present invention makes use of microchannelreactors 320 (FIG. 17) such as those disclosed in U.S. Pat. No.6,192,596 entitled “Active microchannel fluid processing unit and methodof making,” and U.S. Pat. No. 6,622,519 entitled “Process for cooling aproduct in a heat exchanger employing microchannels for the flow ofrefrigerant and product,” each of which is hereby incorporated byreference. Exemplary microchannel reactors 320 for use with the presentinvention are fabricated from stainless steel alloys and includeinterposed microchannels, where a first set of microchannels containcatalysts utilized for Fisher-Tropsch synthesis where the reactants (COand H₂) form hydrocarbons and generate thermal energy, and a second setof microchannels carry a coolant adapted to remove at least a portion ofthe thermal energy generated by the Fisher-Tropsch synthesis.

Referring FIGS. 17-20, a series of microchannel reactors 320 are housedwithin the interior of the vessel 302 and receive a reactant stream withrelatively high concentrations of carbon monoxide and hydrogen by way ofthe reactant conduit 314. A manifold 322 in communication with thereactant conduit 314 is welded to each of the reactors and operative todistribute the reactant stream amongst the six microchannel reactors320. As the reactants flow through the microchannels (not shown),Fischer-Tropsch synthesis catalyst contained within the microchannelsfacilitates an exothermic reaction generating thermal energy. Aninternal coolant is delivered to the microchannel reactors 320 by way ofthe coolant conduit 312 feeding a manifold 324 welded to anddistributing the coolant amongst the six microchannel reactors. In thisexemplary embodiment, the coolant is boiler feed water entering thereactors 320 at approximately 220° C. and exiting the reactors as amixture of liquid water and saturated steam opposite the manifold 324.

Superheated steam enters the reactors 320 by way of the steam conduit310 in order to provide a flowing stream of product from the reactors320. As discussed above, the products from the reactors 320 include highmolecular weight hydrocarbons which may result in partial solidificationwithin the microchannels. To inhibit the solid content of the productsstream from blocking the microchannels, superheated steam is injectedinto the microchannels downstream from the reaction section of themicrochannels to provide a source of thermal energy to the productstream and elevate the temperature within the product stream and ensurethat fluid flow continues. As the product stream exits the reactors 320via a welded manifold 326, the products are collected into a productconduit 328. The product conduit 328 is jacketed by the steam conduit310 and provides a countercurrent heat exchanger providing more thermalenergy (higher temperature steam) to the product stream as it travelsfarther downstream from the reactors 320.

The vessel 302 includes an active level control system (not shown) toinhibit the level of water within the vessel from reaching the outletsof the reactors 320 where water and steam are exiting. An orifice (notshown) within a lower circumferential area of the vessel 302 providesaccess to the water conduit 318 for removal of water from the vessel. Itis envisioned that the water withdrawn from the vessel 302 be routedthrough the coolant conduit 312 to supply the boiler feed water. At thetop of the vessel 302 is the steam outlet conduit 316 operative towithdraw the steam produced within the reactors 320. The active controlsystem is also operative to maintain the fluid surrounding the reactors320 at an elevated pressure so that the pressure exerted upon theexterior of the reactors is not significantly less than the pressuresexerted upon the interior aspects of the reactors.

Those of ordinary skill will understand that the pressure exerted by thefluids surrounding the reactors 320 will vary depending upon theoperating parameters chosen for the reactors. Nevertheless, it is withinthe scope of the present invention that the vessel be constructed towithstand internal pressures of 500 psig. Exemplary materials for use infabricating the vessel 302 include, without limitation, SA 515, SA 516,and 1¼ chrome alloys.

Those of ordinary skill are familiar with commercially availablecatalysts for use in a Fisher-Tropsch synthesis. These catalystsinclude, without limitation, those disclosed and taught by U.S. patentapplication Ser. No. 10/766,297 entitled “Fischer-Tropsch SynthesisUsing Microchannel Technology and Novel Catalyst and MicrochannelReactor,” the disclosure of which is hereby incorporated by reference.

It is also within the scope of the present invention that the reactors320 be removable from the manifolds 322, 324, 326. In this manner, themanifolds 322, 324, 326 are bolted to the reactors 320 with aninterposing gasket to ensure a fluidic seal between the manifolds andreactors. Exemplary gaskets for use with this alternate exemplaryembodiment include, without limitation, Garlock Helicoflex SpringEnergized Seals, graphite gaskets, reinforced graphite, corrugatedmetal/spiral wound gaskets, and elastomeric seals. As discussedpreviously, welding of the reactors 320 introduces high localtemperatures that may degrade or destroy catalyst in proximity to theweld and/or result in delaminations. In addition, the availability toquickly remove one or more reactors 320 from the vessel 302 obviates theneed to provide separate catalyst refurbishment lines. In such analternate exemplary embodiment, the refurbishment of active metalcatalysts can occur away from the pressure vessel 304, as well as theability to perform tests upon the reactors 320 away from the pressurevessel 304.

Following from the above description and invention summaries, it shouldbe apparent to those of ordinary skill in the art that, while themethods and apparatuses herein described constitute exemplaryembodiments of the present invention, the inventions contained hereinare not limited to these precise embodiments and that changes may bemade to them without departing from the scope of the invention asdefined by the claims. Additionally, it is to be understood that theinvention is defined by the claims and it is not intended that anylimitations or elements describing the exemplary embodiments set forthherein are to be incorporated into the meanings of the claims unlesssuch limitations or elements are explicitly recited in the claims.Likewise, it is to be understood that it is not necessary to meet any orall of the identified advantages or objects of the invention disclosedherein in order to fall within the scope of any claim, since theinvention is defined by the claims and since inherent and/or unforeseenadvantages of the present invention may exist even though they may nothave been explicitly discussed herein.

1. A microchannel unit assembly comprising: a removable microchannelunit including an inlet orifice and an outlet orifice in fluidcommunication with a plurality of microchannels distributed throughoutthe removable microchannel unit; and a pressurized vessel adapted tohave the removable microchannel unit mounted thereto, the pressurizedvessel adapted to contain a pressurized fluid exerting a positive gaugepressure upon at least a portion of the exterior of the removablemicrochannel unit.
 2. The microchannel unit assembly of claim 1,wherein: the pressurized vessel includes a docking station adapted tohave the removable microchannel unit mounted thereto and provide fluidcommunication with at least one inlet conduit adapted to carry an inputstream to the removable microchannel unit and at least one outletconduit adapted to carry away an output stream from the removablemicrochannel unit; and the docking station includes an inlet orifice andan outlet orifice, where the inlet orifice of the docking station isadapted to be generally aligned with the inlet orifice of the removablemicrochannel unit to provide fluid communication between themicrochannels and the inlet conduit, and where the outlet orifice of thedocking station is adapted to be generally aligned with the outletorifice of the removable microchannel unit to provide fluidcommunication between the microchannels and the outlet conduit.
 3. Themicrochannel unit assembly of claim 2, further comprising: a retaineroperative to maintain the general orientation of the inlet orifice ofthe docking station with the inlet orifice of the removable microchannelunit, as well as maintain the general orientation of the outlet orificeof the docking station with the outlet orifice of the removablemicrochannel unit; and a first gasket assembly sandwiched between atleast one of the retainer and the docking station, and the removablemicrochannel unit and the docking station, to ensure a fluidic sealtherebetween.
 4. The microchannel unit assembly of claim 3, wherein: theremovable microchannel unit includes at least one side that is tapered;and the docking station includes at least one side that is tapered tocorrespond to the taper of at least the one side of the removablemicrochannel unit.
 5. The microchannel unit assembly of claim 4,wherein: the removable microchannel unit includes two opposing sidesthat are tapered; and the docking station includes two opposing sidesthat are tapered to correspond to the taper of two opposing sides of theremovable microchannel unit.
 6. The microchannel unit assembly of claim5, wherein the retainer is bolted to at least one of the pressurizedvessel and the removable microchannel unit.
 7. The microchannel unitassembly of claim 6, wherein: the two opposing sides of the removablemicrochannel unit that are tapered are tapered outward to provide atleast a partial V-shaped profile; the two opposing sides of the dockingstation that are tapered are tapered outward to provide at least apartial V-shaped profile; the V-shaped profile of the removablemicrochannel unit is seated upon and supported by the V-shaped profileof the docking station.
 8. The microchannel unit assembly of claim 7,wherein: the first gasket assembly is sandwiched between the retainerand the docking station to provide a first fluidic seal; a second gasketassembly is sandwiched between the retainer and the removablemicrochannel unit to provide a second fluidic seal, where at least oneof the first and second gasket assemblies is operative to seal a gapbetween the pressurized vessel and the removable microchannel unit; anda third gasket assembly is sandwiched between the removable microchannelunit and the docking station to provide a sealed fluidic interfacebetween the inlet orifices and the outlet orifices.
 9. The microchannelunit assembly of claim 6, wherein: the two opposing sides of theremovable microchannel unit that are tapered are tapered outward toprovide at least a partially inverted V-shaped profile; the two opposingsides of the docking station that are tapered are tapered outward toprovide at least a partially inverted V-shaped profile; and the invertedV-shaped profile of the removable microchannel unit is adapted to beseated against the inverted V-shaped profile of the docking station. 10.The microchannel unit assembly of claim 9, wherein: the first gasketassembly is sandwiched between the retainer and the docking station toprovide a first fluidic seal; a second gasket assembly is sandwichedbetween the retainer and the removable microchannel unit to provide asecond fluidic seal, where at least one of the first and second gasketassemblies is operative to seal a gap between the pressurized vessel andthe removable microchannel unit; and a third gasket assembly issandwiched between the removable microchannel unit and the dockingstation to provide a sealed fluidic interface between the inlet orificesand the outlet orifices.
 11. A microchannel system comprising: aplurality of modular microchannel unit operations, where each modularmicrochannel unit operations includes a plurality of distributedmicrochannels and at least one inlet orifice and at least one outletorifice in fluid communication with the plurality of distributedmicrochannels; at least one inlet conduit adapted to carry and direct aninlet stream toward at least one of the plurality of modularmicrochannel unit operations; at least one outlet conduit adapted tocarry an outlet stream away from at least one of the plurality ofmodular microchannel unit operations; a support structure including atleast one dock having: at least one inlet stream opening in fluidcommunication with at least one inlet conduit, the inlet stream openingis adapted to interface with the inlet orifice of at least one of themodular microchannel unit operations to provide fluid communicationbetween the plurality of distributed microchannels and the inletconduit, at least one outlet stream opening in fluid communication withat least one outlet conduit, the outlet stream opening is adapted tointerface with the outlet orifice of at least one of the modularmicrochannel unit operations to provide fluid communication between theplurality of distributed microchannels and the outlet conduit; a vesseladapted to contain a fluid exposed to a portion of at least one of theplurality of modular microchannel unit operations; wherein at least oneof the plurality of modular microchannel unit operations is removablymounted to at least one of the support structure and the vessel.
 12. Themicrochannel system of claim 11, wherein the at least one modularmicrochannel unit operation removably mounted to the support structuredoes not necessitate destruction of at least one of the modularmicrochannel unit operation and the support structure to achieveseparation from the support structure.
 13. The microchannel system ofclaim 11, wherein the at least one modular microchannel unit operationremovably mounted to the vessel does not necessitate destruction of atleast one of the modular microchannel unit operation and the vessel toachieve separation from the vessel.
 14. The microchannel system of claim11, wherein the support structure, at least one inlet conduit, and atleast one outlet conduit are mounted to the pressure vessel.
 15. Themicrochannel system of claim 11, wherein: at least one of the pluralityof modular microchannel unit operations includes a microchannel reactor;and at least a portion of the plurality of distributed microchannelscontain a catalyst.
 16. The microchannel system of claim 11, wherein:the support structure is mounted to the vessel; and the vessel includesan opening for receiving the dock, which includes an opening adapted tobe occupied by each of the plurality of modular microchannel unitoperations.
 17. The microchannel system of claim 11, wherein: a firstmanifold in fluid communication with a first inlet conduit distributes afirst inlet stream among the plurality of modular microchannel unitoperations; a second manifold in fluid communication with a second inletconduit distributes a second inlet stream among the plurality of modularmicrochannel unit operations; a third manifold in fluid communicationwith a third inlet conduit distributes a third inlet stream among theplurality of modular microchannel unit operations; and a fourth manifoldin fluid communication with a first outlet conduit collects outletstreams among the plurality of modular microchannel unit operations. 18.The microchannel system of claim 11, wherein: a gasketing materialinterposes at least one of the plurality of modular microchannel unitoperations and provides sealed fluid communication between the at leastone inlet orifice and the at least one inlet stream opening; thegasketing material provides sealed fluid communication between the atleast one outlet orifice and the at least one outlet stream opening; andthe dock is angled to match a corresponding angle of the at least one ofthe plurality of modular microchannel unit operations, where thecorresponding angle is other than completely vertical.
 19. Themicrochannel system of claim 11, wherein: at least one of the pluralityof modular microchannel unit operations includes a series of sequentialmetal plates operative to form a labyrinth of microchannels; and theseries of sequential plates provide two opposite and tapered surfacesthat are adapted to interface two corresponding tapered surfaces of thedock, where the surfaces of the sequential plates are parallel to thetapered surfaces of the dock.
 20. The microchannel system of claim 11,wherein at least one of the plurality of modular microchannel unitoperations exhibits a frustropyramidal portion adapted to be orientedbetween corresponding surfaces of the dock to wedge the least one of theplurality of modular microchannel unit operations between thecorresponding surfaces of the dock.
 21. The microchannel system of claim20, further comprising a removable retainer for mounting the at leastone of the plurality of modular microchannel unit operations to at leastone of the dock and the vessel, wherein the retainer is positionedcircumferentially around a frustum of the frustropyramidal portion. 22.The microchannel system of claim 21, wherein: the frustum ismulti-sided; and the retainer is mounted with removable fasteners to thedock.
 23. The microchannel system of claim 22, wherein: the frustum isgenerally a parallelogram; the retainer is bolted to the dock; and agasketing material interposes the retainer and at least one of the dockand the vessel, where the gasketing material is operative to seal a gapbetween the removable microchannel unit and at least one of the dock andthe vessel.
 24. A process for removing a microchannel unit comprising:disengaging a retainer operative to mount a microchannel unit to asupport structure, where the retainer is adapted to be reusable; andremoving the microchannel unit from the support structure subsequent todisengaging the retainer.
 25. The method of claim 24, wherein: thesupport structure includes a pressurized vessel; and the retainerincludes a bolted assembly and the act of disengaging the retainerincludes at least one of removal or manipulation of bolts of the boltedassembly.
 26. The method of claim 25, wherein: the microchannel unitincludes a microchannel reactor having a catalyst contained therein; thecatalyst is refurbished while the microchannel reactor is disengagedfrom the support structure.
 27. A method of installing a microchannelunit comprising: seating a microchannel unit including: aligning atleast one inlet conduit of the microchannel unit with at least one feedstream conduit of a first preexisting structure, and aligning at leastone outlet conduit of the microchannel unit with at least one productstream conduit of a second preexisting structure; fastening themicrochannel unit in a seated position using removable fasteners.
 28. Amicrochannel unit assembly comprising: a microchannel unit operationincluding: a first set of microchannels in fluid communication with afirst inlet orifice and a first outlet orifice, and a second set ofmicrochannels in fluid communication with a second inlet orifice and asecond outlet orifice; a first inlet conduit in fluid communication withthe first set of microchannels and adapted to direct a first inletstream toward the first set of microchannels; a first outlet conduit influid communication with the first set of microchannels and adapted todirect a first outlet stream away from the first set of microchannels; asecond inlet conduit in fluid communication with the second set ofmicrochannels and adapted to direct a second inlet stream toward thesecond set of microchannels; a pressurized vessel housing at least aportion of the microchannel unit operation therein, the pressurizedvessel adapted to contain a pressurized fluid exerting a positive gaugepressure upon at least a portion of the exterior of the microchannelunit operation; wherein the second outlet orifice is in fluidcommunication with an interior of the pressurized vessel.
 29. Themicrochannel unit assembly of claim 28, wherein: the microchannel unitoperation include a microchannel reactor carrying out a Fischer-Tropschsynthesis; the first inlet stream includes carbon monoxide and hydrogen;the first outlet stream includes hydrocarbons; the second inlet streamincludes liquid water; and the interior of the pressurized vesselincludes liquid water and water vapor.
 30. The microchannel unitassembly of claim 29, wherein: the pressurized vessel includes an outletfor the liquid water; the pressurized vessel includes an outlet for thewater vapor; and at least a portion of the liquid water entering thesecond set of microchannels exits the second set of microchannels aswater vapor.
 31. The microchannel unit assembly of claim 28, furthercomprising an elevated temperature fluid conduit adapted to direct anelevated temperature fluid into the first set of microchannels.
 32. Themicrochannel unit assembly of claim 31, wherein: the elevatedtemperature fluid flows out of the first set of microchannels and intothe first outlet conduit; the elevated temperature fluid conduit jacketsthe first outlet conduit; and the elevated temperature fluid transfersthermal energy to the first outlet stream prior to flowing through thefirst set of microchannels.
 33. A method of carrying out aFischer-Tropsch synthesis comprising: containing, at least partially, amicrochannel unit operation within a pressurized vessel, where themicrochannel unit operation includes a first set of microchannels influid communication with a first inlet conduit, a second inlet conduit,and a first outlet conduit, and where the microchannel unit operationincludes a second set of microchannels in thermal communication with thefirst set of microchannels; reacting carbon monoxide and hydrogen in thepresence of a catalyst within the first set of microchannels to producehydrocarbons; introducing an elevated temperature fluid via the secondinlet conduit downstream from the catalyst within the first set ofmicrochannels; and generating steam in a second set of microchannels,where the steam is vented to the interior of the pressurized vessel.